The present invention is directed to an anchor dowel assembly with a sleeve containing window-like openings in which radially displaceable locking members are positioned so that initially the locking members project into the bore formed in the sleeve. The radial dimension of the locking members is greater than the thickness of the sleeve wall.
In the German Offenlegungsschrift No. 25 35 066 a known dowel is disclosed which is used exclusively in receiving bores with undercuts and the dowel includes locking members supported in window-like openings so that the members can be displaced radially outwardly into the undercut by an expansion member. To effect the radial displacement, the expansion member is rotated and runs in the insertion direction of the dowel into the borehole between the locking members because of a threaded connection. Due to experience with such a dowel, after it is introduced into the receiving bore in the dowel,it is freely rotatable. Accordingly, it is not possible to effect the radial displacement of the locking members to achieve an anchoring effect merely by rotating the expansion member, since the locking member and the sleeve would be rotated ineffectively along with the expansion member due to the threaded connection. To achieve the displacement of the locking members, the sleeve must be secured against rotation along with the expansion member and this requires appropriate auxiliary means engaging the sleeve and a complicated manipulation.